In recent years, in the electronic device member application, not only metals but also many resin materials are used. The resin materials are lightweight and excellent in moldability, as compared to metals, and therefore the application of the resin materials is expected to be expanded. For meeting demands for such an expanded application, particularly, in the advanced material application, resin materials and compositions are required to be further improved in representative resin performances, such as heat resistance, dielectric properties, and moisture resistance reliability, and to have all these performances and further exhibit high flame retardancy.
For example, as resin materials for electronic device members, thermosetting resins, such as epoxy resins, benzoxazine resins, and BT (bismaleimide-triazine) resins, are used. Particularly, the epoxy resins have high adhesive force and chemical resistance and exhibit low shrinkage upon being cured and high strength, and therefore a great amount of the epoxy resins are used. In an attempt to further improve the heat resistance of the epoxy resin, for example, as described in PTL 1, an epoxy resin having a specific aromatic ring structure has been developed.
An epoxy resin composition can be improved in heat resistance not only by improving the structure of the epoxy resin but also by using a curing agent having a characteristic structure. For example, when using an aromatic aminophenol compound as a curing agent, the epoxy resin composition is improved in heat resistance due to a rigid structure derived from the aromatic structure of the curing agent. Especially when such a curing agent is reacted with an aromatic epoxy resin, the epoxy resin composition can be further improved in heat resistance.
As a conventional method for producing an aromatic aminophenol compound, there can be mentioned the following two methods roughly classified:
1) method in which phenol is subjected to nitration, followed by reduction; and
2) method in which an amino group-containing aromatic compound is reacted with a hydroxyl group-containing or methoxy group-containing aldehyde, followed by reduction.
The aromatic aminophenol compound having a benzene ring which is a monocycle is relatively simple in the structure, and therefore an industrializabe technique for producing the compound has been established, although a nitration step is essential. However, for further improving the heat resistance, when a polycyclic aromatic aminophenol compound having a plurality of benzene rings is produced, a reaction of nitration or reduction is used, and thus a safety problem about the production is caused, and further the polycyclic structure is difficult to maintain due to the stringent reaction conditions for nitration or reduction, making difficult the production of the compound. Further, there is a problem in that the reaction must be conducted through a plurality of steps, increasing the production cost.
Moreover, the conventional methods have a disadvantage in that the design freedom is such small that only a polycyclic aromatic aminophenol compound having a limited structure can be produced.